Add --show-lines option for CSV tables

[ajorpheus]

Summary

Adds a --show-lines CLI flag to control display of lines between rows in CSV tables.

Changes

• Added --show-lines click option to enable row separator lines in CSV output
• Updated render_csv() function signature to accept show_lines parameter
• Modified table creation to use the parameter (defaults to False for backward compatibility)

Usage

# Display CSV with lines between rows
rich --csv --show-lines file.csv

# Default behavior (no lines)
rich --csv file.csv